FWIW, I'll also put my 5 cents in the jar. I don't think I'm bringing something new to the discussion, but this is how I currently understand the matters.

When I try to distill a bit what has been said, I have the impression that the concerns boil down to essentially two points:
- Apparently, a subset of gamers misunderstand 'early access' as "It's done, but our marketing team told us that releasing the game on date x will give it the best attention it can get, but if you really want, you can play it now.", or something along those lines.
If one thinks that is what early access is, then (s)he's bound to be upset when the early access price is higher than (or even the same as) retail: "Hey, I payed extra to play this sooner, but the thing is like unfinished or something, wtf! Did I pay extra for *that*? What a rip-off." -- Proceeds to spread bad press about this scandal, and discredits the product.
- Apparently, a subset of kickstarter backers have the impression they simply buy a product when they back something, and do not fully take to heart that they're making an investment in a project that they'd like to see completed, but may fail completely, or fail to live up to all promises. Thinking about kickstarter in this oversimplified way seemingly makes the platform just an elaborate early access point of sale.
If one thinks this is what kickstarter is, then (s)he's bound to be upset when the steam early access price is lower than (or the same as) their pledge: "What the hell, I was like a year early with buying my early access game, and it bought me nothing. Jerks. :-/", maybe even forgetting about some extra goodies they got with the game. -- Proceeds to spread bad press about these corporate jerks and discredits the company.
I personally think that both problems can be alleviated with good two-way communication with the fans/clients, which happens to be something that I think Larian is doing a splendid job at. Of course there will always be people that will ignore all warnings and notes and messages, but I don't think anyone should bother to be bothered by other people's ignorance, because you probably can't do good for them anyway.

In the words of Swen from his blog post: "So yes, some misunderstanding about what’s in an alpha or a beta is inevitable, but I think that as people play more of these early access games, it’s something that’ll correct itself over time and they’ll learn how to judge things." -- I agree.